Tunnelling-induced ground movements in clay

Abstract

A series of plane strain centrifuge model tests of single tunnels in moderately stiff clay has been conducted at City University, London. Ground movements were measured using conventional displacement transducers at the ground surface and by digital image-processing techniques below ground level. The relatively simple tests are shown to result in ground movements which are consistent with field measurements, but the tests produced considerably more high-quality data, which have been analysed to improve predictions of both surface and subsurface movements in the plane transverse to a tunnel in clay. The measured data are assessed against commonly used empirical predictive techniques, indicating some deviations from current practice. A procedure for predicting horizontal movements as a function of the vertical settlement profile is suggested.